New ureido derivatives of isoperthiocyanic acid and the method for their preparation

ABSTRACT

This invention relates to heterocyclic compounds of the formula   WHEREIN Y is selected from the group consisting of oxygen and sulfur and R is a hydrocarbon, said compounds being useful as peroxide inhibitors and corrosion inhibitors.

ilnited States Patent Inventor Raymond Seltzer New York, N.Y. Appl. No.Filed Patented Assignee Nov. 16, 1971 M&T Chemicals Inc. New York, N.Y.

NEW UREIDO DERIVATIVES 0F ISOPERTHIOCYANIC ACID AND THE METHOD FOR THEIRPREPARATION 2 Claims, No Drawings U.S. Cl 260/3063 R, 252/391, 252/402,260/247, 260/3451, 260/3459, 260/3461 R, 260/347.8

Int. Cl C07d 91/70 Field of Search 260/3067, 306.8

Attorneys-Lewis C. Brown, Kenneth G. Wheeless and Robert P. GrindleABSTRACT: This invention relates to heterocyclic compounds of theformula wherein Y is selected from the group consisting of oxygen andsulfur and R is a hydrocarbon, said compounds being useful as peroxideinhibitors and corrosion inhibitors.

NEW UHllElIlDO DERIVATIVES OF TSOPERTHIOCYANIC AC) ANII) THE METHOD FORTHEIR PREPARATION DERIVATIVES OF lSOPERTHlOCYANlC AClD wherein Y isselected from the group consisting of oxygen and sulfur and R is ahydrocarbon.

According to another of its aspects, this invention is a novel processfor preparing heterocyclic compounds of the formula wherein Y isselected from the group consisting of oxygen and sulfur and R is ahydrocarbon, comprising reacting as reactants isoperthiocyanic acid ofthe formula and an organic compound of the formula RNCY wherein Y isselected from the group consisting of oxygen and sulfur and separatingsaid heterocyclic compounds.

The terms isocyanate and isothiocyanate are generally applicable tocompounds containing one of more E=C=Y groups in which Y is oxygen orsulfur. Compounds of this generic definition includes monoisocyanatesand monoisothiocyanates of the general formula RNCY in which R is ahydrocarbon or substituted hydrocarbon selected from the groupconsisting of alkyl, cycloalkyl, alkenyl, alkynyl, aralkyl, aryl,alkaryl, and substituted analogues thereof.

In the isocyanate compound, RNCY, R may be a hydrocarbon radicalpreferably selected from the group consisting of alkyl, alkenyl,cycloalkyl, aralkyl, aryl, alkaryl, including such radicals when inertlysubstituted. When R is alkyl, it may typically be straight chain alkylor branched alkyl, including methyl, ethyl, n-propyl, isopropyl,nH-butyl, isobutyl, secbutyl, tert-butyl, n-amyl, neopentyl, isoamyl,nhexyl, isohexyl, heptyls, octyls, decyls, dodecyls, tetradecyl,octadecyl. etc. Preferred alltyl includes lower alkyl, i.e. having lessthan about eight carbon atoms, i.e. octyls and lower. When R is alkenyl,it may typically be vinyl, allyl, l-propenyl, methallyl buten-l-yl,buten-2-yl, buten-3-yl, penten-l-yl, hexenyl, heptenyl, octenyl,decenyl, dodeeenyl, tetradecenyl, octadecenyl, etc. When R iscycloalkyl, it may typically be cyclopentyl, cyclohexyl, cycloheptyl,cyclooctyl, etc. When R is aralkyl, it may typi cally be benzyl,B-phenylethyl, Y-phenylpropyl, B-phenylpropyl, etc. When R is aryl, itmay typically be phenyl, naphthyl, etc. When R is alkaryl, it maytypically be tolyl, xylyl, p-ethylphenyl, p-nonylphenyl, etc. R may binertly substituted, e.g. may bear nonreactive substituents such asalkyl, aryl, cycloalkyl, aralkyl, alkaryl, alkenyl, ether, halogen,nitro, ester, etc. Typical substituted alkyls include 3-chloropropyl,Z-ethoxyethyl, carboethoxymethyl, etc. Substituted alkenyls include4-chlorobutyl, Y-phenylpropenyl, chloroallyl, etc. Substitutedcycloalkyls include 4-methylcylohexyl, 4- chlorohexyl, etc. lnertlysubstituted aryl includes chlorophenyl, anisyl, biphenyl, etc. lnertlysubstituted aralkyl includes chlorobenzyl, p-phenylbenzyl,p-methylbenzyl, etc. lnertly substituted alkaryl includes3-chloro-5-methylphenyl, 2,6-ditert-butyl-4-chlorophenyl, etc.

Examples of such isocyanate and isothiocyanate compounds include methylisocyanate, ethyl isocyanate, butyl isocyanate, octyl isocyanate,octadecyl isocyanate. vinyl isocyanate, isopropenyl isocyanate, ethynylisocyanate, benzyl isocyanate, phenyl isocyanate, vinyl phenylisocyanate, tolyl isocyanate, ethyl isothiocyanate. and. phenylisothiocyanate, a-naphthyl isocyanate, 4-tolylene isocyanate, andn-hexyl isocyanate. Also included are polyisocyanates andpolyisothiocyantes.

The isoperthiocyanic acid used in the practice of this invention isobtainable by the reaction of an ammonium or an alkali metal thiocyanatewith a mineral acid, e.g. hydrochloric acid.

The process of this invention may be represented by the followingequations:

It is understood that the product of this invention may exist in thefollowing tautomeric forms:

S C S t") wherein R is a hydrocarbon selected from the group consistingof alkyl, cycloalkyl, alkenyl, alkynyl, aralkyl, aryl, alkaryl, andsubstituted analogues thereof.

In an illustrative embodiment the process of this invention comprisesadding an isocyanate compound to a suspension of isoperthiocyanic acidin a suitable solvent. Thus the initial stage of the process comprisingthe reaction of an isocyanate with perthiocyanic acid is preferablyconducted in an organic medium capable of at least partially dissolvingthe reactants. The nature of the solvent is not critical; any suitableorganic solvent may be used. Typical solvents that may be employedinclude ketones such as acetone and methyl ethyl ketone; and ethers suchas dioxane and tetrahydrofuran. The amount of reaction medium isimmaterial as long as a sufficient amount is used to maintain thereaction in a liquid medium.

The process of this invention may be carried out at ambienttemperatures, although a wide range of temperatures are operable.

In the practice of the method of this invention, the relativeproportions of the two reactants, isoperthiocyanic acid and organicisocyanate, are about the stoichiometric ratio of l:l.

The product of the initial stage of the reaction may be recovered byconventional means, e.g. precipitation and filtration, or other suitablemethods dependent upon the physical properties of the product.

This invention is exemplified in the specific example describedhereinbelow, which is understood to be an illustrative and notlimitative embodiment of the invention.

EXAMPLE Preparation of S-phenylureido-S-thione l,2,4-dithiazole 750grams (0.50 mole) of isoperthiocyanic acid was suspended in'3 liters ofdioxane. 59.5 grams (0.50 mole) of phenyl isocyanate was added to theforegoing suspension. The mixture was stirred and refluxed for 210minutes The precipitate a yellow solid was separated, washed withdioxane, and dried. The product 3-phenylureido-5-thione 1,2,4-dithiazole, exhibited a weight of 6.10 grams and a melting point of22022l C.

The compounds of this invention are useful as peroxide inhibitors and ascorrosion inhibitors. The corrosion inhibition tests were conductedusing steel coupons, 3 inches by one-half inch, of 16 gauge steel. Thesteel coupons treated with the compounds of this invention showed nosign of corrosion or rust at the interface after 6 hours of exposure.

The compounds of this invention are also effective in inhibiting theformation of peroxides in ethers. Ethers effectively protected fromperoxidation include tetrahydrofuran, tetrahydrofurfuryl ethyl ether,dihydropyran, tetrahydropyran, 2-methyltetrahydrofuran.2-ethoxytetrahydropyran, and N-methylmorpholine.

Inasmuch as the foregoing specification comprises specific embodimentsof the invention which were selected merely for purposes ofillustration, it is to be understood that the invention includes allvariations and modifications that may be made without departing from thescope as defined in the appended claims.

lclaim:

1. Heterocyclic compounds of the formula wherein Y is selected from thegroup consisting of oxygen and sulfur and R is hydrocarbon selected fromthe group consisting of alkyl of one to eight carbon atoms; phenyl;cycloalkyl selected from the group consisting of cyclopentyl,cyclohexyl, cycloheptyl, and cyclooctyl; benzyl; inertly substitutedalkyls selected from the group consisting of 3-chloropropyl and 2-ethoxyethyl; inertly substituted alkenyls selected from the groupconsisting of 4-chlorobutyl, Y-phenylpropenyl, and chloroallyl; inertlysubstituted cycloalkyls selected from the group consisting of 4-methylcyclohexyl and 4-chlorocyclohexyl; chlorophenyl; substituted aralkylselected from the group consisting of chlorobenzyl, p-phenyl benzyl,pmethyl benzyl; and inertly substituted alkaryl selected from the groupconsisting of 3-chloro-S-methylphenyl, 2-6-di-tertbutyl-4-chlorophenyl.

2. The compound of the formula of claim 1 which is3-phenylureido-S-thione 1,2,4-dithiazole.

2. The compound of the formula of claim 1 which is3-phenylureido-5-thione 1,2,4-dithiazole.